I dont mean this in a bad way, but I really think you are confusing a bunch of things together. The four examples you gave all point towards different directions.
A "know-it-all", or a besserwisser as it's sometimes called (originally from German), is someone thinks s/he knows it all, and feels the need to show/share this knowledge with others by constantly correcting others or dropping tidbits at uncalled times.
Below his dignity to ask questions, would imply that the person can't be bothered to learn, that he cannot accept someone else is more knowledgeable.
Alternatively a person might be too shy to ask a question to a superior, not because of admitting their superiority but more for the fear of admitting to a lack of knowledge and possibly losing the other person's respect.
All in all, if the person in question has the attitude of "what could you possibly know more than me" towards a someone else I would probably start by calling that person arrogant and ignorant, as he would be ignoring and belittling others experience and knowledge.
If that person is additionally a superior (however you define that relationship) I would add the disrespectful and short-sighted, as well as expect him to be fired eventually if this all happens at a workplace :)